((m-n+1)^2 - (m-1+n)^2 )/(4m * (n+1))=(m^2+n^2+1+2m-2mn-2n-m^2-n^2-1-2mn+2m+2n)/(4m*(n+1))=(-4mn+4m)/(4m*(n+1))=4m(1-n)/(4m*(n+1))= (1-n)/(n+1)
((m-n+1)^2 - (m-1+n)^2 )/(4m * (n+1))=(m^2+n^2+1+2m-2mn-2n-m^2-n^2-1-2mn+2m+2n)/(4m*(n+1))=(-4mn+4m)/(4m*(n+1))=4m(1-n)/(4m*(n+1))= (1-n)/(n+1)